Invasive species have played a major role in 60% of known animal and plant extinctions, with a global economic impact that exceeded US$423 billion in 2019, according to the Assessment Report on Invasive Alien Species and their Control approved by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES).
The report, approved Saturday in Bonn, says the costs have quadrupled since 1970 and a conservative estimate is that there are more than 3,500 harmful invasive species affecting ecosystems and the people who depend on them.
Most but not all of the impacts are negative. They include health impacts, with diseases including malaria, Zika and West Nile Fever spread by invasive mosquito species Aedes albopictus and Aedes aegyptii. They also include economic impacts, as is the case on Lake Victoria, where tilapia fisheries have been hard-hit by the growth and spread of invasive water hyacinth (Pontederia crassipes).
“The good news is that, for almost every context and situation, there are management tools, governance options and targeted actions that really work,” said Dr. Anibal Pauchard of University of Concepción in Chile. Pauchard served as a co-chair for the report, alongside Dr. Helen Roy of the UK Centre for Ecology & Hydrology and Canada’s Dr. Peter Stoett of Ontario Tech University.
“Prevention is absolutely the best, most cost-effective option – but eradication, containment and control are also effective in specific contexts,” said Pauchard. “Ecosystem restoration can also improve the results of management actions and increase the resistance of ecosystems to future invasive alien species.”
Border and import controls, and other improved policies on invasive species, can help to limit the impacts of other drivers of biodiversity damage as well. For example, invasive species may play a role in the spread of some wildfires, leading to more carbon emissions than would have occurred due to climate change alone.
“Even without the introduction of new alien species, already established alien species will continue to expand their ranges and spread to new countries and regions,” said Roy. “Climate change will make the situation even worse.”
The Americas accounted for 34% of reported invasive species impacts, with another 31% coming from Europe and Central Asia. A fourth came from Asia and the Pacific with just 7% from Africa. Most of the impacts are observed on land, with the most damaging effects seen on islands; only 24% of reports concerned freshwater or marine habitats. Roy notes the future threats are only expected to increase.
Yet the management goal, as part of the new Kunming-Montreal Global Biodiversity Framework approved last year, is to reduce key invasive alien species by at least 50% by 2030.
“It would be an extremely costly mistake to regard biological invasions only as someone else’s problem,” said Pauchard. “Although the specific species that inflict damages vary from place to place, these are risks and challenges with global roots but very local impacts, facing people in every country, from all backgrounds and in every community – even Antarctica is being affected.”
